1、 Principle of dispersant: 1. The basic purpose of dispersing pigments in the medium by mechanical means is to disperse the oleophilic agglomerated particles caused by drying in the process of pigment manufacturing. When the particle size decreases, the exposed surface area increases, which improves the optical properties of the pigment, such as coloring performance, gloss, brightness, hiding power or transparency.

　　2. In general dispersant grinding system, such as ink and coating, resin is one of the components in the formulation, but resin and dispersant will compete with each other in pigment. The adsorption capacity of dispersant on the pigment surface is also affected by the resin, and the resin and dispersant will compete with each other to adsorb on the pigment surface.

　　However, the difference between dispersant and resin lies in the fastness of the dispersant to the surface of pigment. The dispersant not only has strong adsorption to pigment, but also has good affinity to solvent. In fact, the resin only plays a wetting role on the surface of the pigment. It does not stick to the surface of the pigment for a long time. After a long time, the resin will slowly leave the surface of the pigment and cause flocculation. However, the existence of the resin still hinders the anchoring of the dispersant on the surface of the pigment.

　　Therefore, when selecting resin, the film-forming function brought by resin should be considered, and it is not necessary to select another good wetting or grinding resin. In addition, whether the resin content in the grinding base material is sufficient or not should be considered to maintain the stability of the formula.

　　3. The use of dispersant in the grinding base material, compared with the traditional grinding base material, the key to adjust its formula is the concentration of resin solution. In traditional grinding media, the resin concentration is higher and the amount of pigment can be filled is less. Although the viscosity of the dispersion medium can be reduced and the pigment filling amount can be increased by reducing the resin concentration, the dispersion system is not stable and can not be used in practical production.

　　If a good dispersant is used, the dispersion system can be stable at a lower resin concentration, thus greatly increasing the pigment filling amount in the grinding base material. The space barrier generated by the solvation chain of dispersant in the medium reduces the suction between particles and greatly reduces the grinding viscosity, which is one of the reasons for the increase of pigment filling amount.

　　Under the action of dispersant, the increase range of pigment filling amount varies with the dispersion system, but in the adjustment process, the grinding base material should be kept with moderate viscosity.

　　4. Pigment stability theory the stability of pigment dispersions can be divided into two mechanisms: electrostatic stability and steric stability, both of which require molecules to adsorb the pigment surface.

　　2、 Usage and dosage of dispersant:

　　The amount of dispersant should be determined according to the pigment dispersed, and the amount of dispersant should be based on the formation of a dense monolayer adsorption layer on the surface of pigment. If the dosage is too small, the dispersant can not show its advantages, and too much dosage will affect the stability of grinding. This is mainly because overcrowded dispersant can not fully extend the solvation chain of the dispersant on the surface of the pigment, and a large amount of free dispersant will have a negative impact on the film.

　　In the actual operation process, the approximate amount of dispersant can be calculated according to the theoretical rules, and then float up and down as the midpoint. The relationship between the viscosity, gloss and coloring power of the dispersion system with the amount of dispersant is observed. When the dosage of dispersant is moderate, the viscosity of the dispersion system has an obvious small value, while the gloss and coloring power of the film have a large value.